.. caution::

    If ``timestamp`` is used, ``DateType`` is limited to dates between
    Fri, 13 Dec 1901 20:45:54 GMT and Tue, 19 Jan 2038 03:14:07 GMT on 32bit
    systems. This is due to a `limitation in PHP itself <http://php.net/manual/en/function.date.php#refsect1-function.date-changelog>`_.
